1. Field of the Invention
The invention relates to annunciators and refers more particularly to a circuit for and a method of providing a digital indication of the condition of line voltage and switches in a series circuit including structure for and the steps of sensing the series circuit before the first and subsequent to each switch, and providing separate electronic logic level signals in response to the voltage at the sensed points in the series circuit, encoding the output signals to provide a digital signal representative of the first point at which voltage was lost, and subsequently decoding the encoded signals to provide an output signal for driving a digital display device providing an indication of the point of fault.
2. Description of the Prior Art
In the past, structure for determining which of a plurality of switches in a series circuit has opened first has often been complicated and expensive and sometimes inefficient. Further, such circuits in the past have not always provided a definite indication of which switch opened first and/or a definite indication of line voltage failure. Also, the prior circuits have usually not provided a ready method for ascertaining which is the first open switch in the series circuit prior to the circuit initially being completed. Often, the annunciators of the past have not provided a direct digital readout or have not been fail-safe. Such structures have also often sensed impulses across a switch rather than merely monitoring the signal at the switch which has been undesirable.